Jefferson Lab Weekly Briefs
August 21, 2013
12 GeV Upgrade
The final light guides for the Hall D Barrel Calorimeter (BCAL) have been attached to the calorimeter modules, which in turn have been stacked, all but the last two, into the cylindrical arch shape prior to insertion into the solenoid magnet bore. The light monitoring system for BCAL, built by the University of Athens, is being added as the BCAL sectors are readied. The silicon photomultipliers that sense the light generated in BCAL will be mounted on the light guides using the custom mechanics and cooling structure, once BCAL is inserted into the solenoid magnet bore. The lead-glass Forward Calorimeter, which sits downstream of BCAL, has been stacked into its support frame and is having its readout electronics added. The Central Drift Chamber has had a full checkout at Carnegie Mellon University prior to shipping to Jefferson Lab. The four stations of the Forward Drift Chamber have been assembled onto their support frame and are being readied for cabling. Florida State University continues assembling the time-of-flight wall to be located just upstream of the lead-glass Forward Calorimeter. Preparation has started of the thinned diamonds that will serve as the bremsstrahlung target; scattered electrons from this target will be detected in the tagger hodoscope and tagger microscope, which are being assembled by Catholic University and University of Connecticut staff, respectively. Installation of front-end electronics, data acquisition electronics, online computers and trigger electronics to render all the above equipment ‘live’ is proceeding apace. The solenoid magnet has been re-cooled to liquid helium temperatures and mapped at the planned operating current of 1300 Amps. It has since been warmed up to carry out some planned repairs to its refrigerator.
Center for Theoretical and Computational Physics
A new paper presents a detailed analysis of nuclear effects in inclusive electron scattering from polarized 3He nuclei, both in the nucleon resonance and deep-inelastic regions. Calculations within the weak binding approximation at finite Q2 are compared with the effective polarization ansatz often used in experimental data analyses, and the impact of Δ components in the nuclear wave function and nucleon off-shell corrections on extractions of the free neutron structure are explored. The results will be used to analyze existing and future Jefferson Lab experiments on 3He spin structure functions and their moments.
The mechanical engineering group reports that the installation of 12 GeV beam transport work is progressing well. The majority of elements have been installed in the main accelerator ring. The installation team is focusing on beam pipe and low-conductivity water (LCW) installation.
A design review was performed on the mechanical layout of the beam dump design for Halls A and C for 12 GeV era operation.
The design of the Short Pulse X-ray (SPX) cryomodule continues in preparation for a design review to be held at Argonne National Lab in September. The drawing packages for the cavity string and space frame are in final review.
Facilities Management and Logistics
Intermittent Power Outages Planned for Test Lab Aug. 29
Environment, Safety, Health and Quality
School Buses and Children
The NHTSA also notes that kids' greatest risk for riding a bus is while approaching or leaving it, particularly in the school bus “danger zone,” which is the 10 feet in front, behind and on each side. Kids may not perceive danger from the bus itself and could dart in front of the bus, may walk into traffic, or may start to approach the bus before it has completely stopped. It's important for parents to ensure that their kids know how to board and depart a school bus safely. Check to see if your school has a bus safety orientation for new riders or make a point to get your child on a bus before the big day. The NHTSA also offers tips for school bus safety for drivers, parents and kids. Tell your child, while you have their undivided attention, what is a safe place to be and where to go when boarding and departing a school bus.
Hot Checkout Training Available Online
TIAA-CREF Onsite Individual Counseling Sessions
Tracking Thomas at Jefferson Lab
Narciso Gomez correctly guessed the location for Aug. 14. Honorable mentions go to Brian Kross, Darrell Spraggins, Silvia Niccolai and Casey Heck. Check out Tracking Thomas on flickr for a better view of his last location and this week's new mystery photo.
JLab Calendar of Events
Aug. 19-22: Accelerator Readiness Review
|JLab Weekly Briefs is an ongoing publication providing information on the status of safety, accelerator operations, experiments, free-electron laser, reviews, upcoming activities and special events. Deadline for submission is every Tuesday by 10 a.m. Submit new items to: Public Affairs or contact Kandice Carter at x7263.|